About attaching the propeller - it would appear the manufacturer intends for the prop to go on the shaft, then the cap to be glued on after - but no glue between the cap and the prop, only between the cap and the mounting shaft. The backing plate, spinner, and prop should all be glued together, but not to the cap, or the shaft. Rotating prop! It makes the assembly order a bit odd, but would still let the prop be movable.